How big is a 0.5 carat radiant cut diamond?

By HeyGema™ · Updated

In short

A 0.5 carat radiant cut diamond measures about 5.2 x 4.0 mm. It faces up 2% smaller than a round diamond of the same weight. On a size 6 finger it covers 24% of the width. For the same weight, a round diamond is 5.1 mm.

Carat to mm calculator

About 5.2 x 4.0 mm

An estimate for a well-cut stone. A deep or shallow cut faces up smaller or bigger.

0.5 ct radiant
5.2 x 4.0 mm
0.5 ct round
5.1 mm
Side by side
0.5 ct radiant inside 0.5 ct round
A 0.5 carat radiant diamond beside a 0.5 carat round, to the same scale.

0.5 carat radiant diamond size

A well-cut 0.5 carat radiant cut diamond measures about 5.2 x 4.0 mm (0.20 x 0.16 inches) at a length-to-width ratio of 1.30:1. It faces up 2% smaller than a round diamond of the same weight. It weighs 0.10 grams.

0.5 carat radiant size by length-to-width ratio

The same weight can be long and narrow or short and wide. These are 0.5 carat sizes at each ratio. A longer ratio runs the stone along the finger and makes it look slimmer. The face-up area stays almost the same.

1.00:1
Length x width: 4.5 x 4.5 mm
Width on the finger: 27% of a size 6 finger
1.15:1
Length x width: 4.9 x 4.2 mm
Width on the finger: 26% of a size 6 finger
1.30:1
Length x width: 5.2 x 4.0 mm
Width on the finger: 24% of a size 6 finger
1.40:1
Length x width: 5.4 x 3.8 mm
Width on the finger: 23% of a size 6 finger

0.5 carat radiant on a finger

4.0 mm
4.0 mm stone on a 16.5 mm finger: it covers 24% of the widthA 0.5 carat radiant diamond on a size 6 finger.
4
Finger width: 14.9 mm
Radiant covers: 27%
5
Finger width: 15.7 mm
Radiant covers: 25%
6
Finger width: 16.5 mm
Radiant covers: 24%
7
Finger width: 17.3 mm
Radiant covers: 23%
8
Finger width: 18.1 mm
Radiant covers: 22%
9
Finger width: 18.9 mm
Radiant covers: 21%

Radiant sizes near 0.5 carat

0.25 carat
Length x width: 4.1 x 3.1 mm
Round of the same weight: 4.1 mm
0.33 carat
Length x width: 4.5 x 3.5 mm
Round of the same weight: 4.5 mm
0.5 (this page)
Length x width: 5.2 x 4.0 mm
Round of the same weight: 5.1 mm
0.75 carat
Length x width: 5.9 x 4.5 mm
Round of the same weight: 5.9 mm
1 carat
Length x width: 6.5 x 5.0 mm
Round of the same weight: 6.5 mm

0.5 carat in other shapes

Every row is a well-cut diamond of 0.5 carat. The last column is the face-up size against the radiant.

Round
Length x width: 5.1 mm
Against radiant: +2%
Oval
Length x width: 6.3 x 4.4 mm
Against radiant: +8%
Cushion
Length x width: 4.4 x 4.4 mm
Against radiant: -12%
Princess
Length x width: 4.4 x 4.4 mm
Against radiant: -6%
Emerald cut
Length x width: 5.6 x 4.0 mm
Against radiant: +6%
Asscher
Length x width: 4.4 x 4.4 mm
Against radiant: -13%
Pear
Length x width: 6.7 x 4.4 mm
Against radiant: same
Marquise
Length x width: 8.3 x 4.1 mm
Against radiant: +19%
Heart
Length x width: 5.2 x 5.2 mm
Against radiant: -15%
Trillion
Length x width: 5.6 x 5.6 mm
Against radiant: -11%
Baguette
Length x width: 6.3 x 3.2 mm
Against radiant: same

Questions

A 0.5 carat radiant cut diamond is about 5.2 x 4.0 mm at the usual 1.30:1 ratio.
No. Face-up, a 0.5 carat radiant is 2% smaller than a 0.5 carat round (5.1 mm).
There is no rule. The stone is 27% of the width of a size 4 finger and 22% of a size 8. Compare it with a ring you have tried on in the finger chart above.
Yes. A lab grown diamond has the same density as a mined one, so it measures the same for the same weight.

More size charts